Wednesday, February 6, 2013

Opinion Why We Still Need to Think About Bird Flu

Between Jan. 9 and 15, five people in Cambodia
contracted bird flu, and four died of it within a few days -- four young
girls and a 35-year-old man. Only the first case, an eight-month-old
boy, survived.

This might seem like a minor event, but the World Health Organization
sent rapid response teams into the country to help the Cambodian
ministry of health. They've been looking for more cases and educating
local residents about how to avoid the disease -- even though it's one
of the hardest diseases to catch.
"Bird flu" is a vague term: all influenzas
come from birds, especially domestic poultry, though they sometimes
reach us through pigs and other mammals. The Cambodians had H5N1 flu,
which first got our attention when it broke out among chickens and
humans in Hong Kong in 1997. That outbreak was stopped by killing every
chicken and duck in the region, and banning further imports from the
mainland.
Six years later human H5N1 returned, in
Vietnam, and since then has sputtered away from Indonesia and South
Korea to Egypt and Nigeria.
Between 2003 and the end of 2012, the WHO
confirmed no more than 610 human H5N1 cases, most of them in Vietnam,
Indonesia and Egypt. This, out of a population of over seven billion,
makes it one of the world's rarest diseases.

Rare and dangerous

Its rarity is precisely what makes it so
dangerous. Because it evolved to infect birds, H5N1 isn't designed to
infect mammals. Humans, therefore, are a "naive" population with almost
no immunity to it. That was what scared the health authorities in Hong
Kong, and it's what scares the WHO today.
Out of those 610 cases, 360 people died.
That means the "case fatality rate" (CFR) was 59 per cent. The CFR
varies by country -- it's 35 per cent in Egypt, and 83 per cent in
Indonesia. But globally, three out of five people who catch H5N1 will
die of it within a very few days.
Cambodia has been reporting H5N1 since 2004. Out of 21 cumulative cases by the end of 2012, 19 died -- a 90 per cent CFR. Last year, though, the country had just two cases and one death.
The five new cases, then, are alarming because they've happened so suddenly and so close together. One was in Phnom Penh, Cambodia's
capital. The others were in suburbs and nearby villages. And they
continue to be fatal.